Hydroponic Grow Light Science

In Hydroponic growing we can use what we know about Photosynthesis to our advantage. Photosynthesis means to "put together with light". To keep their food production going plants must have carbon dioxide, water, some form of nutrients and the energy they acquire from light. If any of these elements are missing the food production (photosynthesis) within the plant will stop. Light and the amount of it controls the way all plants grow.

The above image was taken from the SeaWiFS instrumentation aboard a NASA satellite from space. By monitoring the color of reflected light scientists can determine how successful plant life is photosynthesizing on Earth. The green in the image shows the active photosynthesis taking place on Earth. Without light all life on earth would die starting with the plants. In Hydroponic gardening it is important to know that there are many levels of light and it comes in many different spectrum's. Let's look at the science of light and how it affects plant life and our Hydroponic systems.

FOOT CANDLE: A unit of luminance. 1 foot candle equals 1 lumen per square foot of area and is approximately 10.76391 Lux.LUX: International system of illumination. Basically this is based on 1 lumen uniformly distributed over an area of 1 meter.

LUMEN: The basic unit of measurement for light. 1 candle shines at about 12 lumens. This is only designed as a measurement for human eyes and not plants.

COLOR RENDERING INDEX: Also know as CRI, an international system to measure light on a scale from 0 to 100. Natural daylight is 100. This is only designed as a measurement for human eyes and not plants.

PAR: Photosynthetic Active Radiation. This is the light energy available for Photosynthesis by plants. This is a scale that was designed to be used for plants.

COLOR TEMPERATURE: A temperature scale used to describe colour temperature in Kelvin or the K rating of a light source. This is a scale that can be used to determine light for plants indicating the different color spectrums that are used by the plants.

Now that you probably know more about light classifications than most people let's see how all of this affects a plant's growth including the flowering and fruiting phases. We will also learn how Hydroponic plant growth can be controlled with the correct Hydroponic grow lights.

Hydroponic Grow Light Science - PAR

All plants, not just in Hydroponics, use just a very narrow band of the electromagnetic spectrum of the Photosynthetic Active Radiation scale or PAR. PAR is the part of the light that plants actually see. Humans see light in a totally different way than plants do. This light that plants see can be measured on a Nanometer scale. The light that plants see is in the Nanometer spectrum's of 360 to 760 Nanometers.

These color spectrum's of light include some ultra violet rays which are shorter light rays and also some infrared light waves which are longer light rays. If you look at the overall light color spectrum these nanometer ranges will be in the blue and red parts of the overall light color spectrum. This knowledge can be used in our Hydroponic gardening to grow larger and healthier Hydroponic plants.

Grow Light Science - Wavelengths

Having said all of that, we know through extensive experimentation that plants primarily use blue light in the range of 380 to 500 Nanometres and red light in the 600 to 740 Nanometre range.

Plants perceive these wavelengths of light through pigments that absorb the energy from the light. These pigments allow the plant to perceive the amount of light and the type of wavelengths in preparation to store the energy for photosynthesis.Plants will then utilize this energy with water and carbon dioxide for the production of photosynthates which are food for the plant's growth. The green light of the overall color spectrum is reflected back by the plants and the whole rest of the overall light color spectrum is virtually invisible or unseen by the plants. We can take what we know about this plant physiology and light spectrum and use it in our Hydroponic gardening.

So, Lets have a look at different light spectrum in nature and how they help to tell the story of how different color spectrum of light influence a plant's overall growth. If we can recreate what nature does so well, our Hydroponic gardening can be much more successful. Let's look at what nature can teach us about light spectrum and how it can relate to Hydroponic plant growth.

Grow Light Science - Mother Nature

For our Hydroponic gardening we can use what we know about nature. As the seasons change here on Earth so do the light rays and the color spectrum of those light rays. As we go into summer the days are shorter and the color spectrum of the light rays go from blue to red.On a hot summer day the light level may be at 10,000 foot candles.

On a cloudy winter day it may only be at 500 foot candles. Blue light activates crypt o chrome pigments that activate correct vegetative growth in plants. It also decreases the spaces between leaves so you get more compact bushy growth.

As we go into summer the red wavelengths trigger hormonal changes in many plants which cause flowering and fruiting. In Hydroponic gardening, the same reactions can be created by changing from blue spectrum wavelength bulbs to red spectrum wavelength bulbs. There are even narrow spectrum bulbs that even take it a step further by creating wavelengths in the far red and far blue spectrum. We can use blue spectrum 6500K lighting with our Hydroponic plants to create more vegetative growth in the beginning plant stages. Blue light run for about 16-18 hours would recreate the Season of spring and the production of leaves and branches.

We can then change our Hydroponic lighting to the red spectrum of 3000K for a shorter period of about 12 hours to recreate the Season of summer. This will induce flowering and fruiting of the Hydroponic plants. We can take what we know about color spectrum and Hydroponic plant growth to choose a variety of Hydroponic grow lights depending on what we want to achieve in our Hydroponic plants.